I had a 751A years ago...great rig, IMO better than a lot of the new SDR radios including my IC7300...
Many if not all will eventually need to be recapped as mine was. Again years ago it wasn't that expensive back then and I found a fellow back East who had a shop and routinely did this repair. He knew exactly which capacitors needed replacing and did them all. He also did a realignment and the radio worked great again. I don't remember the shop name.
So, I'm guessing your 751A is in need of recapping, but I'm not an expert here. Do a search for ICOM repairs shops, the good techs will know what is wrong with your rig...however, I doubt ICOM factory would be willing to help. One last thought, have you searched YouTube for advice?
GL/73